Flat contact piece



May 10, 1966 w. HOLZER FLAT CONTACT PIECE 2 Sheets-Sheet 1 Filed May 14,1964 /wkm ///X//////f 1\\ 1 V 7/ //fl 3 1 16 2 I N V E NTO R 1 WALTERHOLZER wad/n.

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INVENTOR WALTER HOLZER ATTIJRNEY5 United States Patent 3,250,885 FLATCONTACT PIECE Walter Holler, Drostwcg 19, Meersburg (Bodensee), GermanyFiled May 14, 1964, Ser. No. 367,534 Claims priority, applicationGermany, May 18, 1963, H 49,212; June 11, 1963, H 49,413

20 Claims. (Cl. 200-166) The invention relates to a flat contact in theform of a stamped member and for use chiefly in printed circuits wherethe circuits are provided an on insulating base. The contact isconnected to the base without screws by means of springs, and is movedby switching cams. The contact-making part of the fiat contact, whichremains connected to the base, is additionally designed as a hearing sothat movement is possible when the raising contact making part, whichco-operates with an opposed contact and which is moved by an actuatingcam, operates satisfactorily.

In a flat contact of this type which is connected to and co-operateswith a base, the invention aims to design the contact both so that it isaccessible from one side when a plurality of bases with circuits printedon them are superimposed and also so that two adjacent flat contacts canact as a double contact.

In one embodiment in which a plurality of superimposed bases printedwith circuits are provided the problem of the invention is solved, inthat the fiat contact has a portion, for example an angled portion,extending through the base, that said portion ends in an electricallyconductive bearing lying on the undermost base, that the connection tothe base is provided by springs bearing on the cover of the casing, andthat the springs also press the actuating cam for the raising contact onthe upper most base of the fiat contact onto the switching cam located,for example, between the bases.

In this embodiment the switching cam is provided between twocircuit-carrying bases. It may, for example, be a control disc havingconcentric tracks, raised and lowered portions being provided within thetracks. The raised and lowered portions are sensed by the actuating camand thereby move the part of the flat contact which has to be raised.

An important factor is that one can assemble and dismantle the fiatcontact from one side without removing the switching cam or having todismantle the bases.

An important feature of another embodiment is that adjacent flatcontacts can be fixed together and can be used both as double contactsand as main and preliminary contacts. This last term refers to the factthat the contacts open and close in succession; the last contact to belifted off and then replacedvon the opposed contact or printed circuitis defined as the preliminary contact. This suffers all the consumptionso that the following contact, which is provided with particularly goodcontact material, is spared.

In one embodiment wherein superimposed printed circuits are providedwith the switching cam arranged anywhere between them the problem of theinvention is solved, in that the flat contact has a portion, for examplean angled portion, extending through the top-most and upper bases, thatsaid portion ends in an electrically conductive bearing lying on theundermost base, that the connection to the base is provided by a springbearing on the cover of the casing, and that the spring also pressesthe. actuating cam for the raising contact on 3,250,885 Patented May 10,1956 most and/or all the bases and acted on by the spring. The portionwhich is connected to the fiat contact and which is pressed onto theundermost base (by) the spring is in the form of a bearing so that thereis a rolling movement rather than a sliding one when the actuating camis moved by the switching cam.

According to the invention the spring, which provides the resilientnon-positive connection between the hearing and the printed circuit, ismounted on a guide pin located above the top-most base and guided in thecover of the casing.

This construction ensures that the minimum of labour is required forassembly and dismantling; the cost of the top-most base of the flatcontact onto the switching making it is also very low.

If a switching cam in the form of a control disc is used it is essentialfor the angled end of the flat contact to be far enough away from theactuating cam to extend outside the control disc comprising theswitching cam.

Another possibility is for the bearing to rest on the conductive trackof a printed circuit and for the sensing contact to co-operate with astationary contact mounted on a stationary opposed bearing surface, forexample on a casing.

In order to make the flat contact stand upright the stationary contactcan either be in the form of an upright guide or an upright guide forthe second angled arm of the flat contact may be provided on the printedcircuit, on the conductive tracks of which the bearing rests.

Further according to the invention an additional guide pin is providedand extends through a slot in an opposed bearing surface, for examplethrough the cover of the casing, thus providing a very simple uprightguide for the flat contact.

In the double contact embodiment Where there are two adjacent flatcontacts acting as a double contact the raisable ends of the flatcontacts are, according to the invention, interconnected by anentrainment member provided on one fiat contact. p

This member guarantees that the contact making ends are either liftedsimultaneously or else are lifted insuccession always in the samesequence. Thus the contact resistence is decreased in any event, foreither the contact surface is enlarged by the simultaneous operation ofthe contacts or one contactif there is a preliminary and a main contactthe main contact-is provided with contact material which greatly reducesthe transitional resistance; this contact material can be used because apreliminary contact closes or is lifted first and keeps the maincont-act free from consumption.

The entrainment member may take a great many different forms. One is ashoulder provided on the flat contact which is raised first. When thecontact has been raised the shoulder bears on a projection from theother flat contact arranged at a spacing above the first, so that theflat contact having the projection is the preliminary contact for theother flat contact.

If there is a spacing between the entrainment member and the projectionmoved thereby, then the two contacts act as a preliminary and a-rnaincontact.

In another construction the entrainment member is a shoulder provided onthe flat contact which is lifted first, and the projection from theother flat contact rests on the entrainment member when the contact isclosed.

In this embodiment the two double contacts operate simultaneously.

In the embodiment where the double contact is formed by a preliminary'and a main contact it is desirable for the raising ends of the flatcontacts to comprise different material known per se for main andpreliminary contacts.

For example, the preliminary contact may be provided with atungsten-alloyed material capable of absorbing a,250,as

3 contact consumption, in which case the main contact would be only asilver-alloyed material.

The double contacts may be used both with printed circuits and withother opposed contacts allowing a high degree of cont-act consumption.

It is important that the first flat contact to be raised Anotherpossibility is for the shoulder of one fiat contact, which acts as anentrainment member, to be designed as a bearing for the projection fromthe other contact arranged at a spacing thereabove, so that when theactuating cam is moved towards the entrainment member each end of thedouble contact is raised, acting as a main and preliminary contact, andwhen the actuating cam is moved towards the other end this other end isalso raised, acting as a main and preliminary contact, the ends whichare not raised always resting resiliently on the opposed contact, forexample a printed circuit.

If the actuating cam is arranged as described it is possible to raiseboth sides of the fiat contact either as a main or preliminary contactor as simultaneously operating contacts. The cam must then always beactuated only in the direction of the contact to be raised. In this waythe life of the contacts can be greatly lengthened since there are now,so to speak, four contacts available, located on one or other side ofthe flat contact depending on the direction in which the cam isactuated.

Manufacturing technique may be simplified if the projection from oneflat contact is pressed out in the form of a lug. V

The double contact may also be in the form of a stamped portion.

It is desirable for the portion stamped out of the flat contacts toreceive the cylindrical fastening spring tobe asymmetrical, so that theapertures are aligned when the projection from one flat contact lies inthe aperture in the other contact.

The spring, which also serves to fasten the fiat contacts, acts as areturning force when the contact has been raised. If the contacts arenot raised simultaneously, i.e., if they are used as a preliminary andmain contact, then the asymmetrical aperture ensures that both contactsare always spring-fettered. This measure is particularly important ifthe contacts are used, for example, in washing machine controls, wherevibration is inevitable.

If the contacts are used as preliminary and main contacts it isimportant that the flat contact carrying the actuating cam should be thepreliminary one.

The preliminary contact, i.e., the one carrying the actuating cam, alsocarries the entrainment member. As the entrainment member is first moveda sufficient distance and the contact is thus lifted ofi the base as apreliminary contact until it reaches the projection, the correctsequence is always followed in contact making, or when the process isreversed this contact is again the first to touch down on the base.

Examples of the invention are illustrated in the drawings which, inconjunction with the description thereof, contains further features.

In the drawings:

FIG. 1 is a part sectional diagram showing the flat contact according tothe invention mounted in a cam switch with two superimposed printedcircuits,

FIG. 2 is a part sectional plan view of the cam switc according to FIG.1,

FIG. 3 shows a modified embodiment of a fiat contact t according to theinvention mounted as a switching member between a printed circuit and astationary contact,

FIG. 4 is a front elevation of one fiat contact with the projection,

FIG. 5 is a plan View of FIG. 1,

FIG. 6 is a side elevation of FIG. 1,

FIG. 7 is a front elevation of the other flat contact with theentrainment member or bearing,

FIG. 8 is a plan view of FIG. 7,

FIG. 9 is a side elevation of FIG. 7,

FIG. 10 is a front elevation of the two fiat contacts forming the doublecontact in an embodiment where they act as preliminary and main contact,

FIG. 11 is a side elevation of FIG. 10,

FIG. 12 shows the preliminary contact already raised and the maincontact still making contact as the actuating cam moves in one directionshown by the arrow,

FIG. 13 shows the preliminary contact raised and the main contact stillmaking contact as the cam is actuatedv in the other direction shown bythe arrow, and

FIG. 14 is a plan view of a printed circuit comprising the'doublecontact.

FIG. 1 shows a cam switch with a printed circuit in the form of a base 2with conductive coatings 3 printed on it provided on the base plate 1thereof. A second printed circuit, also comprising an upper base 4 withconductive coatings 5 printed on it, is provided parallel with and abovethe base 2 and is attached, for example, by means of spacing sleeves 6and screws 7. A cam plate 8 is fixed on a shaft 9 between the bases 2, 4and can be turned axially by means of a rotary knob 19. The cam plate 8is provided in known manner with concentric grooves 11 having cam-likeraised or lowered portions 12 depending on the application. The camswitch is suitably covered, for example by a casing cap 13 detachablyfixed to the base plate 1. In the embodiment illustrated the angled endis provided at the end of the flat contact so that the latter has anangular shape. Reference will hereafter be made to a first angled arm,which is provided above the topmost base, and to a second angled arm,

which adjoins the first at right angles and extends through the bases.

FIGS. 1 to 3 show the first angled arm 14 and the second angled arm 15,which together form the flat contact. The end of the second arm 15 formsa bearing 16, is substantially semi-circular and bears on the conductivecoating 3 with a resilient frictional connection owing to the action ofa spring 17. The spring 17 is pushed over a guide pin 18 mounted on thefirst angled arm 14 near the vertex and in the opposite direction fromthe second arm 15. The guide pin 18 extends into a slot 19 in the casingcap 13, in the inner wall of which the spring 17 is supported. Thesimplest way of mounting the fiat contact in the switch is to push thesecond angled arm 15 through a guide slot 24 in the upper base 4 and toinsert the cam slide 20 at the free end of the first arm 14 through aguide passage 21 through the upper base 4 into the concentric groove 11in the cam plate 8 below. When all the flat contacts have been arrangedas described above the casing cap 13 is put on, so that the guide pins18 enter the guide slots 19 and the springs 17 receive a bias whereby,as already described, the bearing 16 makes contact with the conductivecoating 3 and the sensing contact 22 near the cam slide 20 forms aresilient frictional connection with the conductive coating 5 of theupper base 4. As the guide pin 18 is nearer to the bearing 16 than tothe sensing contact 22, the bearing 16 will move along the conductivecoating 3 with a resilient frictional connection even if the cam slide24 is raised by a cam 12 on the rotating cam plate 8 and the sensingcontact 22 is consequently also raised in the direction of the arrow 23.Although the fiat contact is kept upright by the guide slots 19, 24 andthe guide aperture 21, it may be an advantage to provide a guide sleeve25 for the second arm 15 on the base 2.

FIG. 3 shows a modified embodiment of this flat contact according to theinvention in the form of a switching member between the conductivecoating 3 on the base 2 and a stationary contact 26, the latter beingmounted on a stationary opposed bearing surface, for example on thecasing cap 13. It will be seen from FIG. 3 that a second guide pin 27may be arranged on the first angled arm 14 near the cam slide 20 also inthe opposite direction from the second arm 15. The pin 27 may extendinto a guide slot 19 in the casing cap 13, thereby greatly improving theupright guidance of the fiat contact. As FIG. 3 also shows, the guidepin 18 and, if desired, the guide pin 27 may be extended and providedwith a terminal strip 28, for example for attaching flexible leads (notshown) in a conductive manner.

FIGS; to 14 show the base 29. This may be made of hard paper or a pieceof sprayed plastic. Conductive contact tracks 31, 32 are provided on thetop 30 of the base in known manner. The base contains a flat slot 34also acting as a guide for the flat contacts 33, 35 which together formthe double contact. The fiat contacts are arranged upright as stampedmembers and can either be raised in the direction of the arrow 37 by theactuating cam 36 or vertically reciprocatedin the direction of the arrow46 also.

Depending on the direction 37, 46 in which the cam 36 is moved, theraising contact 38 will be on one side of the fiat contacts 33, 35 andthe stationary contact 39 onthe other. The raising contact 38 is at theleft in FIG. 12 and at the right in FIG. 13, relatively to the stamping43. The stamping 43 has two lugs 44, 45 which act as a guide for thecylindrical spring 411. The spring 41 is supported against the underside47 of the base 29, as the slot 34 is correspondingly narrower. Thisattachment can be seen in FIG. 14 and in the main application. The widthof the projection 42 from the two flat contacts 33, 3-5 is approximately equal to the length of the slot 34.

In FIG. 4 one flat contact 35 also has a projection 48 which is markedin it as a lug during the stamping process. The other fiat contact 33has a shoulder 49 which entrains the projection 48 when the contact 33moves in the direction of the arrow 50. The flat contacts 33, 35 carrylugs 51, 52 at both ends, these being designed as contacts to form aconnection with the opposed contacts provided by the conductive tracks31, 32.

In FIG. 10 the projection 48 is provided at a distance 53 above theshoulder 49. In this position, however, the lugs 5.1, 52 rest firm-1y ontheir opposed contacts, i.e., on the conductive contact tracks 31, 32 bythe action of the cylindrical spring 41. If, as shown in FIG. 12, theactuating cam 36 is moved in the direction of the arrow 37, then the lug51 of the fiat contact 33 is first lifted off the contact track 31 untilthe shoulder 49 acting as an entrainment member is applied to theprojection 48. The

gap 54 now left between the lug 51 and the contact track 31 as shown inFIG. 12 makes this lug into a preliminary contact for the subsequentlymoved flat contact 35, the lug 51 of which is raised later.

If the entraining cam 36 is moved in the direction of the arrow 46 asshown in FIG. 13, then it is the lugs 52 which now act as stationarycontacts 39 and remain on the conductive contact track 31, the lug 5 1of the flat contact 33 being lifted off the contact track 32 first untilthere is a gap 54 corresponding to the gap 53 in FIG. 10. The shoulder49 then entrains the projection 48. 'The shoulder 49 may also berounded, i.e., designed as a bearing for the projection 48, in whichcase, as shown in the rest position in FIG. 10, there is no gap 53between the projection 48 and the shoulder or entrainment member 49designed as a bearing. Here the lugs 51 or 52' will be lifted ofi theconductive tracks 31 or 32 whether the cam is actuated in the directionof the arrow 46 or 37, so that there is now a true double contact.

I claim:

1. In a switch gear assembly having at least a first printed circuitplate, a fiat contact piece of stamped metal disposed in an uprightposition within said switch gear assembly, one end of said contact piecebeing adapted to act simultaneously as a contact and as a bearingsurface, and the other end of said contact piece having a contactportion and a cam follower portion, a cam movably mounted within saidswitch gear assembly, said contact piece having a projection disposedbetween the ends thereof and off center with respect thereto, saidprojection of said contact piece projecting into a guide aperture in astationary portion of said switchgear assembly and a helical springdisposed on said projection, said spring being compressed between saidcontact piece and a portion of said switchgear assembly, said springurging said one end of said contact piece into contact with said printedcircuit plate and said cam follower portion of said other end of saidcontact piece into contact with said cam.

2. The flat contact piece of claim 1 including a second fiat contactpiece disposed within said switchgear assembly adjacent said fiatcontact piece, said contact piece being connected to said second contactpiece by an entrainment member such that when said contact piece iscaused to be raised, said second contact piece is raised by saidentrainment member.

3. The flat contact piece of claim 1 wherein said projection on saidcontact piece is a guide pin, and said spring is mounted on said guidepin and wherein said switchgear assembly includes a casing cover, saidcasing cover having a guide aperture into which said guide pin projects.

4. The flat contact piece of claim 1 wherein said other end of saidcontact piece is in the form of a first angled arm and said one end ofsaid contact piece is in the form of a second angled arm, said secondangled arm being in the form of a bearing.

5. The flat contact piece of claim 4 including a second printed circuitplate disposed parallel to said first plate, wherein said bearing ofsaid second angled arm contacts a conductive coating on said firstprinted circuit plate and the contact portion of said first angled armcontacts a conductive coating on said second printed circuit plate, saidsecond plate having a guide slot through which said second angled arm ispassed.

6. The fiat contact piece of claim 4 including a stationary contact on astationary bearing surface mounted on said switchgear assembly whereinsaid bearing of second angled arm contacts a conductive coating on saidprinted circuit plate and said contact portion of said first angled armcontacting said stationary contact.

7. The fiat contact piece of claim 6 wherein said stationary contact isdesigned as an upright guide for said first angled arm.

8. The flat contact piece of claim 5 wherein said first printed circuitplate is provided wit-h a guide sleeve for keeping said second angledarm in an upright position.

9. The flat contact piece of claim 4 wherein said first angled arm isprovided with a second projection in the form of a guide pin, saidsecond projection being disposed near the free end of said first angledarm, said second projection projecting in a direction opposite from saidsecond angled arm, said switchgear assembly having a slot through whichsaid second guide pin extends.

10. The flat contact piece of claim 3 wherein said guide pin iselongated, the end of said pin being designed in the form of aconnecting cover plate for flexible leads.

11. The fiat contact piece of claim 9 wherein said second guide pin iselongated, the end of said second pin being designed in the form of aconnecting cover plate for flexible leads.

12. The flat contact piece of claim 2 wherein said entrainment membercomprises a shoulder provided on said first fiat contact piece and aprojection provided on said second contact piece at a distance abovesaid shoulder such that when said first contact piece is raised, saidshoulder thereon will bear against said projection on said secondcontact piece thereby to raise said second contact piece, said secondcontact piece being the preliminary contact for said first contactpiece.

13. The fiat contact piece of claim 2 wherein said entrainment member isa shoulder provided on said first fiat contact piece, said second fiatcontact piece having a projection which bears against said shoulder ofsaid first contact piece when said first contact piece is closed.

14. The flat contact piece of claim 2 wherein the end of said firstcontact piece adapted to be raised and the end of said second contactpiece adapted to be raised are comprised of different contact materials.

15. ,The fiat contact piece of claim 2 wherein said first fiat contactpiece is adapted to be raised first byv the action of said cam on saidcam follower portion of said trainment member comprises a shoulder onsaid first contact piece and a projection on said second contact piecespaced above' said shoulder such that when said cam follower portion ofsaid first contact is caused to move in a direction towards saidentrainment member, .the ends of said contact pieces nearest saidentrainment member will be raised, said contact pieces thus acting as amain and preliminary contact and such that when said cam followerportion is moved towards the ends opposite from said entrainment member,the opposite ends of saidcontact pieces will be raised, thus also actingas main and preliminary contacts whereby the ends of said contact pieceswhich are not raised always remain in contact with their respectiveopposed contact surface.

18. The flat contact piece of claim 2 wherein said entrainment memberincludes a projection pressed out in the form of a lug from said firstcontact piece.

19. The flat contact piece of claim 2 wherein said first and said secondcontact pieces have asymmetrical apertures which are adapted to receivesaid spring, said apertures being aligned when said entrainment memberacts on said second contact piece.

20. The flat contact piece of claim 12 wherein-contact piece having saidcam follower portion is designed as the preliminary contact.

3,188,435 6/1965 Rugsten 200-166 ROBERT s. MACON, Acting PrimaryExaminer.

KATHLEEN H. CLAFFY, Examiner.

H. O. JONES, Assistant Examiner.

1. IN A SWITCH GEAR ASSEMBLY HAVING AT LEAST A FIRST PRINTED CIRCUITPLATE, A FLAT CONTACT PIECE OF STAMPED METAL DISPOSED IN AN UPRIGHTPOSITION WITHIN SAID SWITCH GEAR ASSEMBLY, ONE END OF SAID CONTACT PIECEBEING ADAPTED TO ACT SIMULTANEOUSLY AS A CONTACT AND A BEARING SURFACE,AND THE OTHER END OF SAID CONTACT PIECE HAVING A CONTACT PORTION WITHINA CAM FOLLOWER PORTION, A CAM MOVABLY MOUNTED WITHIN SAID SWITCH GEARASSEMBLY, SAID CONTACT PIECE HAVING A PROJECTION DISPOSED BETWEEN THEENDS THEREOF AND OFF CENTER WITH RESPECT THERETO, SAID PROJECTION OFSAID CONTACT PIECE PROJECTING INTO A GUIDE APERTURE IN A STATIONARYPORTION OF SAID SWITCHGEAR ASSEMBLY AND A HELICAL SPRING DISPOSED ONSAID PROJECTION, SAID SPRING BEING COMPRESSED BETWEEN SAID CONTACT PIECEAND A PORTION OF SAID SWITCHGEAR ASSEMBLY, SAID SPRING URGING SAID ONEEND OF SAID CONTACT PIECE INTO CONTACT WITH SAID PRINTED CIRCUIT PLATEAND SAID CAM FOLLOWER PORTION OF SAID OTHER END OF SAID CONTACT PIECEINTO CONTACT WITH SAID CAM.